There are certain circumstances in which it is desired to electrically stimulate tissue and/or record electrical signals received from such tissue via blood vessels. For example, U.S. patent application Ser. No. 10/744,319, which is expressly incorporated herein by reference, describes a method of treating neurological disorders by intravenously delivering stimulation leads within the brain, thereby obviating the need to invasively create a burr hole in the cranium of the patient.
Despite the minimally invasive benefits provided by these types of procedures, it is preferable that thrombosis formation caused by the blockage of blood flow through a vessel be prevented. It is also preferable that the electrical energy delivered by the vessel implanted electrode lead be as efficient as possible. For example, when treating a neurological disorder using electrical energy, it is desirable that the magnitude of the electrical energy be sufficient to cause sub-threshold stimulation of the targeted brain tissue. Due to the relatively low resistance of blood versus the relatively high resistance of vessel walls, however, the electrical energy is likely to follow the path of least resistance, i.e., through the blood stream, rather than the vessel wall. The gain of the implanted stimulation device could be increased in order to overcome the power losses through the bloodstream. Invariably, this may potentially cause poor sub-threshold stimulation of the target area, or worse, stimulation of a non-targeted region of the brain. Increasing the gain can also impact the system efficiency by reducing the battery life of the implanted stimulation source.
Thus, there remains a need to provide improved intravascular electrode leads that are capable of more efficiently transmitting electrical energy into vessel tissue and receiving electrical energy from vessel tissue, while minimizing the occlusion of blood flow.